The influence of Au nuclei layer on formation and photoelectrochemical properties of Cu2O thin films

Abstract

The smooth and uniform Cu2O thin films were prepared by electrodeposition with the introduction of Au nuclei layer. The influence of Au nuclei layer on the formation of these thin films was investigated by scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and the optical absorption (UV–vis/DR) methods. Smooth and uniform Cu2O thin films without any islands and pinholes are formed when the electrodeposition is conducted after sputtering Au nuclei layer on ITO. Au nuclei layer provides much larger surface area, enhances the Cu2+ ion migration, and consequently prompts the deposition of Cu2O nuclei on Au nuclei layer to form smooth and uniform Cu2O thin films. Further, the Au nuclei layer plays an important role in improving photoelectrochemical performance of Cu2O thin films. The samples with Au nuclei layer exhibits increased absorption and red shift of absorption edge. The observed steady-state photocurrent of samples with Au nuclei layer is much higher than that of samples without Au nuclei layer as a result of the formation of space charge region in Cu2O thin films when the Au and Cu2O are in contact, which greatly improves the production and separation of photo-induced electrons and holes.